Extracts of bone, cementum, dentin, and enamel are being investigated in order to identify specific proteins and to characterize their structure and biological function. Major emphasis will be placed on cementum proteins. A heat labile, trypsin sensitive protein (Mr about 65,000) with chemotactic activity for 'osteoblast-like' cells has been identified and partially purified from guanidine extracts of demineralized rat bone matrix powder and from guanidine EDTA extracts of embryonic human bone. Extracts of adult human bone did not stimulate bone cell migration. In addition extracts of calf teeth including amelogenins, enamelins, and guanidine EDTA extracts of cementum and dentin have no chemotactic activity. The major non-collagenous proteins in bone are glycoproteins. Therefore, the synthesis of glycoproteins by osteoblasts (17/28), a cell line obtained from a rat osteosarcoma are being investigated. These studies indicate that the glycoproteins being secreted are mainly of the complex form. Future studies are directed at investigating the significance of glycoproteins in osteo-genesis and in particular to determine whether this activity is under hormonal control.